Subversion Repositories planix.SVN

/*
 * The `cd' shell.  
 * Just has cd and lc.
 */

#include <u.h>
#include <libc.h>
#include <bio.h>

char *pwd;
char *root = "/";

void
usage(void)
{
        fprint(2, "usage: cdsh [-r root]\n");
        exits("usage");
}

int
system(char *cmd)
{
        int pid;
        if((pid = fork()) < 0)
                return -1;

        if(pid == 0) {
                dup(2, 1);
                execl("/bin/rc", "rc", "-c", cmd, nil);
                exits("exec");
        }
        waitpid();
        return 0;
}

int
cd(char *s)
{
        char *newpwd;
        int l;

        if(s[0] == '/') {
                cleanname(s);
                newpwd = strdup(s);
        } else {
                l = strlen(pwd)+1+strlen(s)+1+50;       /* 50 = crud for unicode mistakes */
                newpwd = malloc(l);
                snprint(newpwd, l, "%s/%s", pwd, s);
                cleanname(newpwd);
                assert(newpwd[0] == '/');
        }

        if(chdir(root) < 0 || (newpwd[1] != '\0' && chdir(newpwd+1) < 0)) {
                chdir(root);
                chdir(pwd+1);
                free(newpwd);
                return -1;
        } else {
                free(pwd);
                pwd = newpwd;
                return 0;
        }
}

void
main(int argc, char **argv)
{
        char *p;
        Biobuf bin;
        char *f[2];
        int nf;

        ARGBEGIN{
        case 'r':
                root = ARGF();
                if(root == nil)
                        usage();
                if(root[0] != '/') {
                        fprint(2, "root must be rooted\n");
                        exits("root");
                }
                break;
        default:
                usage();
        }ARGEND;

        if(argc != 0)
                usage();

        cleanname(root);
        if(cd("/") < 0) {
                fprint(2, "cannot cd %s: %r\n", root);
                exits("root");
        }

        Binit(&bin, 0, OREAD);
        while(fprint(2, "%s%% ", pwd), (p = Brdline(&bin, '\n'))) {
                p[Blinelen(&bin)-1] = '\0';
                nf = tokenize(p, f, nelem(f));
                if(nf < 1)
                        continue;
                if(strcmp(f[0], "exit") == 0)
                        break;
                if(strcmp(f[0], "lc") == 0) {
                        if(nf == 1) {
                                if(system("/bin/lc") < 0)
                                        fprint(2, "lc: %r\n");
                        } else if(nf == 2) {
                                if(strpbrk(p, "'`{}^@$#&()|\\;><"))
                                        fprint(2, "no shell characters allowed\n");
                                else {
                                        p = f[1];
                                        *--p = ' ';
                                        *--p = 'c';
                                        *--p = 'l';
                                        if(system(p) < 0)
                                                fprint(2, "lc: %r\n");
                                }
                        }
                        continue;
                }
                if(strcmp(f[0], "cd") == 0) {
                        if(nf < 2)
                                fprint(2, "usage: cd dir\n");
                        else if(cd(f[1]) < 0)
                                fprint(2, "cd: %r\n");
                        continue;
                }
                fprint(2, "commands are cd, lc, and exit\n");
        }

        print("%s\n", pwd);
}